Diffusion apparatus

ABSTRACT

DIFFUSION APPARATUS, PREFERABLY IN THE FORM OF A DIFFUSION TOWER, IS ESPECIALLY USEFUL IN CONNECTION WITH THE MANUFACTURE OF SUGAR FROM BEETS OR SUGAR CANE. THE STARTING MATERIAL IS COMMINUTED BY CRUSHING, SLICING OR SHREDDING AND FED THROUGH THE APPARATUS IN COUNTER CURRENT FLOW TO AN EXTRACTION LIQUID, BY MEANS OF A HOLLOW SHAFT CONVEYOR, COMPRISING INNER AND OUTER STAGGERED TRANSPORTING BLADES SPACED FROM EACH OTHER AND FORMING IN EFFECT TWO SEPARATE FEED WORMS, BOTH OF WHICH HAVE PREFERABLY THE SAME PITCH DIRECTION.

April'lO, 1973 F. MUSHACK 3,726,715

DIFFUSION APPARATUS Filed April 13, 1971 2 Sheets-Sheet 1 Franz Mus/kick icran Inventor: 7

10, MUSHACK I v DIFFUSION APPARATUS Filed April 13, 1971 2 Sheets-Sheet 2 lnren! Franz Mush United States Patent Office 3,726,715 Patented Apr. 10, 1973 3,726,715 DIFFUSION APPARATUS Franz Mushack, Wolfenbuttel, Germany, assignor to Braunschweigische Maschinenbauanstalt, Braunschweig am Alten, Bahnhof, Germany Filed Apr. 13, 1971, Ser. No. 133,530 Claims priority, application Germany, June 29, 1970, P 20 32 014.3

Int. Cl. C13d 1/00, 1/12 U.S. Cl. 127-5 16 Claims ABSTRACT OF THE DISCLOSURE Diffusion apparatus, preferably in the form of a diffusion tower, is especially useful in connection with the manufacture of sugar from beets or sugar cane. The starting material is comminuted by crushing, slicing or shredding and fed through the apparatus in counter current flow to an extraction liquid, by means of a hollow shaft conveyor, comprising inner and outer staggered transporting blades spaced from each other and forming in eifect two separate feed worms, both of which have preferably the same pitch direction.

BACKGROUND OF THE INVENTION The present invention relates to a diffusion apparatus, more specifically to a diffusion tower for use in connection with the manufacture of sugar. Such diffusion towers are generally used for extracting certain components from comminuted, sliced, crushed or shredded vegetable material, for example sucrose from shredded sugar beets and/ or sliced sugar cane, whereby the vegetable material is transported upwardly through the tower from the lower end to the upper discharge end by means of conveyor elements and in counter current flow to an extraction liquid.

Heretofore, such diffusion towers have been increased in size, especially in their height and in their diameter, in order to satisfy the ever increasing output requirements. As a result, it was necessary to also substantially increase the diameter of the shafts carrying the conveying or transporting elements in order to be able on the one hand, to attach the required transporting elements to the periphery of the shaft and, on the other hand, to keep the circumferential speed difference in radial direction along the transporting elements as small as possible.

Thus, increasing the size has its limitation, especially also with regard to the increased forces which require additional structural efforts in connection with the increased output.

Moreover, for a given through-put and through-flow diameter of the inner space of the tower the increase of the shaft diameter as well as of the diffusion tower requires an additional structural effort or additional structural features which, in the light of the enormous initial investment costs, may determine the profitability of the plant.

OBJECTS OF THE INVENTION In view of the foregoing, the invention aims at achieving the following objects singly or in combination:

To increase the throughput or output capacity of diffusion towers without substantially increasing their over-all dimensions, whereby said additional structural effort or features in the construction of a diffusion tower having said increased output capacity are kept to a minimum;

To construct the through-flow or passage cross-section of a difiusion tower in such a manner that its size is substantially independent of the shaft diameter;

To utilize a hollow shaft, so that the space inside said hollow shaft may be employed as additional diffusion space without thereby influencing the diameter of the diffusion tower;

To increase the output capacity of diffusion towers regardless of their given size or rather to use the given size more effectively for the diffusion purpose;

To control the duration of the feed advance of the shredded vegetable material, while simultaneously assuring an intimate contact between the vegetable material and an extraction fluid;

To provide in addition to said hollow shaft conveyor further feed advance means for said comminuted vegetable material;

To provide means for separately feeding the comminuted vegetable material into two separate diffusion or extraction spaces;

To completely separate the two diffusion spaces from each other so that they may, if desired, be used for different diffusion or extraction processes;

To provide discharge means for the comminuted vegetable material which assure an efficient and simultaneous removal of said material from the two separate diffusion spaces; and

To construct the diffusion apparatus in such a manner that sealing problems are avoided and thus any undesired seepage of the extracted components is prevented.

SUMMARY OF THE INVENTION According to the invention there is provided a diffusion apparatus, especially a diffusion tower for extracting certained components from comminuted vegetable material, especially sugar beet shreds and sliced sugar cane, wherein the vegetable material is transported by means of conveyor elements from a lower portion of the diffusion tower in a counter current flow relative to an extraction liquid and, wherein said conveyor elements are attached to the inside as well as to the outside surface of a hollow shaft. A hollow shaft requires a minimum of material for making it and it may be provided with a sufficient rigidity by selecting the necessary diameter without influencing or affecting the overall diameter of the diffusion tower by said hollow shaft diameter selection. These features permit the use of the invention also in connection with diffusion towers having a smaller output capacity, whereby even in these instances, a substantial structural advantage is achieved.

Another advantage of the invention is seen in the fact that the substantial waste of space prevailing in conventional diffusion towers is avoided. The diameter of the shaft in conventional diffusion towers generally is several meters primarily due to said reasons mentioned above, namely the arrangement of the transporting elements along the shaft, whereby such conventional shafts take up a substantial space inside the diffusion tower which space is lost for the diffusion process. Accordingly, the :use of the shafts according to the invention achieves along with the more efficient use of the space an enormous increase in the output capacity.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention may be clearly understood, it will now be described, by way of example, with reference to the accompanying drawings, wherein:

FIG. 1 is a longitudinal sectional view through a diffusion tower according to the invention illustrating a schematic representation of such tower;

FIG. 2 is a section along the section line II-II of FIG. 1; and

FIG. 3 illustrates a schematic top view of a group of discharge blade means arranged at the discharge end of the diffusion tower according to FIG. 1.

3 DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS FIG. 1 illustrates a diffusion tower according to the invention comprising for example, an upright cylindrical housing 1 supported on a foundation 1. The top portion of the housing 1 is closed by an oil drip pan 2 which catches any oil which might drip downwardly from the drive means arranged above the oil drip pan 2. The oil drip pan thus closes the diffusion space or spaces inside the housing 1.

A supporting column 3 extends from the foundation 1' through the entire length of the housing 1, preferably centrally thereof, and has at its upper end a bearing portion 4, preferably of reduced diameter, which is secured in a gear or drive support member 10 arranged on top of the housing 1. The reduced diameter upper end 4 of the column 3 serves simultaneously as a bearing pin for the hollow shaft 6 which has attached to its upper end a ring gear or toothed wheel 5, for example by a weldment 5', for rotatably supporting the hollow shaft 6 at its upper end on the journal pin or bearing portion 4.

The lower end of the hollow shaft 6 is also rotatably supported relative to the column 3 or relative to the housing 1 as will be described in more detail below. Thus, the hollow shaft may be rotated clockwise or counter-clockwise by any suitable drive means, for example one comprising at least two drive motors 7 attached to the gear or drive support 10 and operatively connected to the toothed wheel 5 through pinions 8.

In the preferred embodiment, the supporting column 3 is itself rigidly held at its lower and upper ends. The supporting column 3 may itself be a hollow cylindrical body. This feature has been found to be highly satisfactory in practice. According to another embodiment of the invention, the supporting column 3 which extends longitudinally through the entire length of the hollow shaft 6, may be mounted for rotating the supporting column either in the direction of rotation of the hollow shaft 6 or in an opposite direction. In this embodiment, an additional feed advance will be imparted to the comminuted starting material by the rotation of the column 3 as will be described in more detail below with reference to the so called retarding members.

In the lower part of the housing 1, there are arranged one or several intermediate sieves or filters 9 through which the extracted components are removed from the diffusion apparatus. These sieves or filters 9 are easily replaceable or exchangeable and may be constructed as a multipart unit which forms a boundary for the ring space between the supporting column 3 and the inner wall surface of the housing 1. In the shown embodiment, the sieves 9 extend underneath the two diffusion spaces 63 and 64. The diffusion space 63 extends between the supporting column 3 and the hollow shaft 6, whereas the diffusion space 64 extends radially outwardly from the hollow shaft 6 toward the inner wall surace of the housing 1. The juice produced during the extraction is filtered by said sieves 9 into a so called juice space 11 provided underneath the sieves in the lower portion of the housing 1. The juice is then removed from the juice space 11 through collection pipes 12.

The starting material from which certain components are to be extracted by diffusion, is supplied to the above mentioned two separate diffusion spaces 63 and 64 through separate feed-in or inlet pipes I16 and 17. The starting material, for example comminuted or shredded beets which have been scalded prior to feeding them into said diffusion spaces, is pumped into the diffusion spaces after the admixture of a predetermined quantity of pre-heated raw juice. The feed-in or inlet pipes 16 and 17 are located with their tower entering ends just slightly above the sieves 9 in the lower part of the diffusion tower in order to utilize efficiently the entire length of the apparatus.

The starting material is transported upwardly through the spaces 63 and 64 by the rotation of the hollow shaft 6 which is provided with conveying elements, such as transporting blades 18 and 19 attached to the hollow shaft 6. This transportation of the starting material from the lower portion of the diffusion tower toward the upper portion of said tower takes place in a counter current flow relative to the down-flow of an extraction liquid. The extraction liquid is slightly acidic, so called fresh water and, if desired, may partially comprises so called press water which is a liquid extracted from the lixiviated material under presure. The extraction liquid is admitted to the upper portion of the diffusion tower through a respective inlet 65, the details of which are not shown.

As mentioned, the conveying elements comprise transporting blades 18 and 19 which cooperate with so called retarding members 20 and 30. The retarding members 20 are attached to the inner surface of the housing 1, whereas the retarding members 30 are attached to the outer surface of the supporting column 3 as may be seen in FIG. 1. The transporting blades 18 and 19 are spaced from each other and staggered. The retarding members 20 reach into the spacings between the blades 19 and toward the outer surface of the hollow shaft 6 but out of contact therewith. The retarding members 30 reach into the spacings between the transporting blades 18 and toward the inner surface of the hollow shaft 6 but also out of contact therewith. Preferably, the staggering of the transporting blades 18 and 19 is such that these blades form two interrupted feed worms, preferably, but not necessarily, having the same direction of pitch. The just described combination of the transportaing blades I18 and 19 with the respective retarding members 20 and 30 according to the invention results in an especially advantageous and specific manner of transporting the material from which components are to be extracted because it assures a very intimate or intensive contact between the upwardly moving material and the down-flowing extraction liquid. This advantage is assured in both diffusion spaces 63 and 64.

It is desirable to provide the lowest transporting blades 18' and 19 with stripping means not shown but which glide along the upper surface of the sieves 9 in order to prevent clogging of the sieves.

The retarding members 20 and 30 which reach into the spacings between the transporting blades 18 and 19 are made, for example of flat, narrow sheet metal strips and if desired, may be hinged or pivoted for tilting or rotational movement about their longitudinal axis. In any event, these retarding members 20 and 3t) influence and thus contribute to controlling the dilfusion process.

In the diffusion tower or apparatus according to the invention, it is further possible to control the diffusion process by adjusting the temperature inside the diffusion tower. Further control is possible by regulating or adjusting the liquid level and/or the transport velocity of the material which is subjected to the extraction process. Especially the latter control is possible by simply adjusting the revolutions per minute of the hollow shaft 6. The just mentioned combinations of adjustments provide an optimum control of the diffusion process.

As mentioned above, the starting material is fed to the two separate diffusion spaces 63 and 64 through said separate inlet means 16 and 17. This feature of the invention has the advantage that the two diffusion spaces in the diffusion tower according to the invention may be operated practically independently of each other, so that, if necessary or desired, these spaces may be utilized for different extraction processes simultaneously.

In this connection it should be mentioned that the starting material may be adapted to increase its transportability into the tower by means of pumps. This may be accomplished in a known manner by admixing to the comminuted material a suitable liquid, for example, water, or especially in connection with sugar beet shreds,

raw juice previously extracted may be added to the starting material.

The duration of the diffusion process depends on the duration of time required for transporting the material from the inlet means 16 and 17 into the upper region of the housing 1 where the material is lixiviated and thus ready for removal out of the tower. This is accomplished by at least one discharge screw or worm 31 which is so located in the upper end of the housing 1 that it reaches into an area adjacent to an opening 33 in the hollow shaft 6. Preferably two discharge worms are provided which operate in opposite discharge feed advance directions and which are arranged on two opposite sides of the hollow shaft 6 as well as in parallel to each other. These discharge worms are highly efficient and thus prevent an accumulation of material especially in the diffusion space 64 surrounding the hollow shaft 6. According to the invention, the discharge worms serve simultaneously also for the discharging of the lixiviated material which is transported through the inner diffusion space '63. For this purpose the hollow shaft 6 is provided with openings 33. The discharging may further be improved by attaching discharge blades 34 to the upper end of the supporting column 3 as shown in FIG. 3. These discharge blades 34 may, for example, be relatively narrow sheet metal strips which are bent in the direction of the circumference of the supporting column 3, whereby the discharge blades are adapted to push the lixiviated material out of the space inside the hollow shaft 6 through the opening 33 and into the space surrounding the hollow shaft 6 and thus into the effective range of the discharge worms 31.

Incidentally, the housing 1 is provided with lateral extensions 66 in which the ends of the discharge worms 31 are supported in a known manner. These extensions may simultaneously comprise discharge openings 32 through which the material is removed out of the diffusion tower for further treatment by means not shown.

It should be noted that the discharge openings 32 are located at the ends of said lateral extensions 66, whereas the openings 33 are evenly distributed about the circumference of the upper end of the hollow shaft 6. The discharge blades 34 are rigidly attached to the supporting column 3 and the direction of bending of these discharge blades 34 corresponds to the direction of rotation of the hollow shaft 6, so that the lixiviated material which due to the rotation of the hollow shaft 6 also moves in the direction of said rotation, is moved along the discharge blades 34 through the openings 33' as described above.

In order to properly guide the hollow shaft 6 at its lower end there are provided bearings 35 which in the embodiment of FIG. 1 are located, for example, between the lowest inwardly reaching retarding members 20' and the outer surface of the hollow shaft 6. Instead of this arrangement or in addition thereto, bearings such as shown at 35 may also be provided between the inner surface of the hollow shaft 6 and any one of the outwardly reaching retarding members 30, preferably the lowest retarding members.

With regard to FIG. 1 it should be noted that the transporting blades 18 and 19 as well as the retarding members 20 and 30 fill the entire length of the diffusion spaces 63 and 64.

Although specific embodiments of the invention have been described, it is to be understood that it is intended to cover all modifications and equivalents within the scope of the appended claims. Thus, the invention is also applicable to any diffusion apparatus in which the starting materials from which certain components are to be extracted are advanced by means of conveying elements.

I claim:

1. A diffusion apparatus for extracting components from comminuted vegetable materials, comprising an upright housing having a lower and an upper end, first inlet means located at said lower end for feeding said com minuted vegetable material into said housing at said lower end thereof, second inlet means located at said upper end for admitting an extraction liquid into said housing at said upper end thereof whereby the extraction liquid flows downwardly, discharge means for said comminuted vege table material located at said upper end of said housing, conveying means, means for rotatably supporting the conveying means in said housing, drive means operatively connected to said conveying means for rotating the latter, said conveying means comprising a hollow shaft having an inner and an outer surface, conveying elements attached to said inner and outer shaft surfaces, whereby two separate conveying paths are provided through which said comminuted vegetable material is transported simultaneously upwardly both inside and outside of the shaft from said first inlet means at the lower end to said discharge means, at the upper end of the housing in countercurrent movement to the downward flow of said extraction liquid, and outlet means arranged at the lower end of said housing for removing extracted components from said housing.

2. The diffusion apparatus according to claim 1, wherein said two separate conveying paths provide a first diffusion space located between said housing and said hollow shaft, and a second separate diffusion space located between the hollow shaft and said column, said first inlet means for said comminuted vegetable material comprising two separate inlet ports and means for connecting said inlet ports separately to the respective one of said diffusion spaces at the lower end of said housing.

3. The diffusion apparatus according to claim 1, further comprising oil drip means located between said discharge means and said drive means.

4. The diffusion apparatus according to claim 1, wherein said outlet means comprise replaceable sieve means insertable into said housing at said one end thereof.

5. The diffusion apparatus according to claim 1, wherein said hollow shaft has opening means at said upper end, said discharge means comprising worm means located at said upper end of said housing and sufiiciently adjacent to said opening means in the hollow shaft, whereby said worm means discharge the comminuted vegetable material transported by all of said conveying elements.

6. The diffusion apparatus according to claim 5, wherein said worm means comprise two worms arranged on opposite sides at the upper end of the hollow shaft, said two worms having oppositely directed pitches, whereby said comminuted vegetable material is discharged from said housing in opposite directions.

7. The diffusion apparatus according to claim 5, further comprising discharge blade means attached to said column and located so as to reach toward said opening means and thus toward said worm means.

8. The diffusion apparatus according to claim 1, wherein said supporting means for rotatably supporting said conveying means comprise a column extending longitudinally through said hollow shaft, and means for mounting said column in said housing.

9. The diffusion apparatus according to claim 8, wherein said mounting means rigidly hold the column in position to prevent rotation of the column.

10. The diffusion apparatus according to claim 8, wherein said mounting means for said column permit rotation of the column relative to said hollow shaft.

11. The diffusion apparatus according to claim 8, wherein said column is a substantially hollow, cylindrical body.

12. The diffusion apparatus according to claim 8, wherein said mounting means for said column permit rotation of the column, and wherein said retarding members attached to said column are shaped to provide an additional feed advance for said comminuted vegetable material.

13. The diffusion apparatus according to claim 8, wherein said housing has an inner wall surface and said column has an outer wall surface, said conveying elements comprising transporting blades attached to the inner surface and to the outer surface of said hollow shaft, said transporting blades having predetermined spacings therebetween, said transporting blades being staggered relative to each other, said apparatus further comprising retarding members attached to said inner wall surface of the housing and to said outer wall surface of the column, said retarding members being positioned so that the retarding members reach into said spacings between adjacent transporting blades toward said hollow shaft but out of direct contact therewith.

14. The diffusion apparatus according to claim 13, wherein said supporting means for rotatably supporting said conveying means comprise bearing means arranged between any one of said retarding members and said hollow shaft.

15. The diffusion apparatus according to claim 8, wherein the staggering of said transporting blades inside and outside said hollow column is such that the blades form two separate worms.

16. The diffusion apparatus according to claim 15, wherein both worms have the same pitch direction.

References Cited UNITED STATES PATENTS MORRIS O. WOLK, Primary Examiner S. MARANTZ, Assistant Examiner U.S. Cl. X.R. 

